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https://issues.apache.org/jira/browse/OPENJPA-736?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12702866#action_12702866
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Milosz Tylenda commented on OPENJPA-736:
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Omitting an identity column is not the problem. The MySQL issue is that it does
not allow the retrieval of generated column by its actual name - coulmn name is
always "GENERATED_KEY". The PostgreSQL issue is that it requires exact case in
column name passed to Connection.prepareStatement("insert into
IdentityGenerationType (someData) values('gktest')", new String[]
{"orderid[case matters here]"});
Looks like the solution is to pass identity column name thru DBDictionary case
conversion and to get generated column value by using column index. MySQL,
PostgreSQL and DB2 accept this. I will see what about MS SQL Server when I
manage to install it. The MS JDBC 2.0 driver suggests it behaves much like
MySQL [1].
[1] http://msdn.microsoft.com/en-us/library/ms378445.aspx
> Combine insert and select SQL together for generated Id
> strategy=GenerationType.IDENTITY
> -----------------------------------------------------------------------------------------
>
> Key: OPENJPA-736
> URL: https://issues.apache.org/jira/browse/OPENJPA-736
> Project: OpenJPA
> Issue Type: Improvement
> Affects Versions: 1.3.0
> Reporter: Fay Wang
> Assignee: Milosz Tylenda
> Fix For: 1.3.0
>
> Attachments: openjpa-736.patch
>
>
> Currently if the strategy of the generated id is GenerationType.IDENTITY,
> when an entity object is created, openjpa will generate two SQL statements.
> The following is an example running on DB2:
> (1) INSERT INTO EntityA (col1, col2, col3, version) VALUES (?, ?, ?, ?)
> [params=(int) 1, (int) 1, (int) 1, (int) 1]
> (2) SELECT IDENTITY_VAL_LOCAL() FROM SYSIBM.SYSDUMMY1
> A performance improvement is to take advantage of the "select from final
> table" feature in DB2 to combine the insert and select statement into a
> single SQL statement as shown below:
> SELECT id FROM FINAL TABLE (INSERT INTO EntityA (col1, col2, col3, version)
> VALUES (?, ?, ?, ?) )
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